Monday, May 18, 2015

In, on, and around the house

In the corner of my study a big very handsome Cellar Spider has been living for the past two or three years. She seems to feed quite well on spiders that wander into the house. She can catch spiders much bigger than she is by wrapping them up carefully at arm's length, which in her case is a good safe distance away.

 Lately she had been growing quite fat, which indicated she was filling up with eggs.

The local males had noticed this as well. Last week when I looked into her web, at least four hopeful males were hanging around in it. They were nervous around this spider hunter, and probably with good reason. You will understand why, when I explain some of the intricacies of spider mating. First note the male's heavy equipment on the palps on either side of his face. These carry intricate vessels that the male fills with semen when he is approaching a female.

Now here is the female from underneath.

The dark slit near the base of her abdomen has in its center the epigynum, into which the male (the female's deadly fangs hanging over his head) must pump the semen he holds in his palps. This risky maneuver is preceded by a great deal of stroking from the tip ends of his own very long legs, while he unfurls his apparatus and tries to judge her mood.

 Suddenly he dives in, does his job in less than a second, and dives away as fast as he can.

He was successful. In about a week she was cradling her new eggs.

About the same time the eggs appeared, Cheryl and I were outside and noticed what at first looked like a small ant walking along on the lid of our garbage can. But when we looked more closely, we saw it was a kind of jumping spider (Synemosyna formica) which mimics ants (no one knows exactly why, but perhaps it's because ants are known to be full of formic acid and therefore not very tasty to predators). This one walked along on six legs with an ant-like gait, and since, being a spider, it had eight legs, and no antennae, to complete its mask it carried its second pair of legs in the air and waved them like antennae.

On top of the lid near it was an ant just the size and color of the spider and so similar in appearance we decided this was the model the spider was imitating.

(This ant apparently led a warrior life; note the decapitated head of another ant which still has its jaws locked on this ant's antennae.)

From there we walked around the corner of the house not twenty feet and saw a completely unrelated spider (Two-banded Antmimic, Castianeira cingulata) which appeared to be imitating the same ant (only this time waving its first pair of legs like antennae).

And a few minutes later we had another nice observation. I went to check a chrysalis that was hanging on the back wall of my study, and a Question Mark butterfly had eclosed. It was so fresh it still had a number of delicate tints on its wings that would soon wear off.

Not a bad day, and we had scarcely stepped outside the house.

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